The problem is, however, that people who crave fast food tend to crave a lot of it, not merely the snack-size portions that are typically delivered on a plastic tray when you spend $1 or $2. So what happens? You eat your $1 snack, and then, since you’re in the restaurant already and you’re still hungry, you spend $6 more to fill your belly.

Menu Items to Get You in the Door More Often
Most people need to drink more than they eat. McDonald’s seems to know this quite well, seeing as they’ve actively tried to draw in customers eager to quench their thirst, with promos such as $1 fountain drinks (actually aimed to compete with 7-Eleven more so than with other fast-food joints), and with “premium” coffee that tastes way better than the old stuff they used to serve.

Again, the point is not so much to sell the customer a cheap drink (though that’s good too because these drinks cost next to nothing to produce), but to get customers in the door—where they’re a lot more likely to buy food than if they were still outside the store. This is the same basic reason why chains like McDonald’s and, more recently, Starbucks, offer free Wi-Fi. According to one study, customers who head to McDonald’s for “free” Wi-Fi typically wind up spending $5.25 an hour on food and beverages while they’re there.